[fatjonny]

"It’s worth noting that the prototype Carmack is demoing wasn’t made by him, but by another Texan builder of VR headsets. It’s using the same tech and principles as Carmack’s own version, which was unfortunately unable to make the trip to E3."

It sounds like he is making his own headset as well. The demo was not on his, though.

[varikin]

That was my impression. It sounds like he is really just looking at all options to figure out what does and does not work and why. To that extent, he is building and modifying hardware to experiment while also working with manufacturers.